ocr: 641 TROUBLESHOOTING GUIDE SYMPTOM POSSIBLE SOLUTION Blank screen on power up. Check External Power Supply U4 (KERNAL ROMI, U17 (PLA) U7 (6510 MPUI, U3 (ROM) U8 (7406 IC), U19 (VIC II) U9-U12 (4164 RAM) U21-U24 (4164 RAM) VR2, CR4, VR1 Out of memory error on power up. Check U9-U12 (4164 RAM) U21-024 (4164 RAM) **** USE DIAGNOSTIC TEST - DISK No cursor displayed. Check U7 (6510 MPU) Intermittent blank screen. Intermittent graphics. Powers up with graphic display and Check U14 (74LS258 IC) blinking cursor. Powers up with all the characters Check U26 (74LS373 IC) displayed as blocks. Intermittent ...
